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A GeoVision Micro™ colour video camera was used to investigate the internal structure of 11 boreholes at Haut Glacier d'Arolla, Switzerland. The boreholes were distributed across a half-section of the glacier, with closest spacing towards the glacier margin. The boreholes were used to investigate the hydrology of the glacier through automatic monitoring of borehole water level and electrical conductivity (EC) at the glacier bed. EC profiling was undertaken in several boreholes to determine the existence of water quality stratification. Temporal variations in EC stratification were used to infer borehole water sources and patterns of water circulation. Borehole video was used to confirm the conclusions made from these indirect sources of evidence, and to provide an independent source of information on the structure and hydrology of this temperate valley glacier. The video showed variations in water turbidity, englacial channels and voids, conditions at the glacier bed and down-borehole changes in ice structure. Based on the video observations, englacial channels accounted for approximately 0·1% of the vertical ice thickness, and englacial voids for approximately 0·4%. Overall, the video images provided useful qualitative and semi-quantitative data that reinforce interpretations of a range of physical and chemical parameters measured in boreholes. © 1997 by John Wiley & Sons Ltd.
Copland et al. (Sat,) studied this question.